Dear All, I am a developer working on an application developed on Lion using Xcode 4.3.2. One of the modules of the app is to load an NSBundle dynamically and use the same to query some information. I find that when I try to unload the bundle, the application crashes a few seconds later and the calls tack in crash report is as provided below. I believe this type of error happens when user tries to release the same object twice. It tried running the NSZombieEnabled technique along with Xcode but to no avail. Code: Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x000000000396d310 VM Regions Near 0x396d310: mapped file 000000000395a000-0000000003960000 [ 24K] r--/rwx SM=COW /Applications/########.app/Contents/Resources/information.png --> MALLOC metadata 0000000003974000-0000000003975000 [ 4K] r--/rwx SM=ZER Application Specific Information: objc: garbage collection is OFF Thread 0 Crashed:: Dispatch queue: com.apple.main-thread 0 com.apple.CoreFoundation 0x9c120fc1 CFRelease + 49 1 com.apple.CoreFoundation 0x9c1698e6 -[__NSArrayI dealloc] + 246 2 libobjc.A.dylib 0x9367754e _objc_rootRelease + 47 3 libobjc.A.dylib 0x93678c58 (anonymous namespace)::AutoreleasePoolPage::pop(void*) + 404 4 com.apple.CoreFoundation 0x9c14be05 _CFAutoreleasePoolPop + 53 5 com.apple.Foundation 0x95e4476e -[NSAutoreleasePool drain] + 131 6 com.apple.AppKit 0x9c370cbd -[NSApplication run] + 791 7 com.apple.AppKit 0x9c601c59 NSApplicationMain + 1054 8 com.App.MyApp 0x0000323d start + 53 In my application which is multithreaded, I load the bundle in a different thread (not the main thread) and unload it in a different thread (this too is not the main thread). Could this possibly be resulting in the crash? Should the bundle load and unload operation be performed on the same thread? Can you guys also please let me know as to what info you guys can extract from the call stack above? Thanks & Regards.